Recently, Unmanned Aerial Vehicles (UAV) have opened up unparalleled opportunities for alpine glacier monitoring, as they allow for reconstructing extensive and high-resolution 3D models. In order to evaluate annual ice flow velocities and volume variations, six yearly measurements were carried out between 2015 and 2020 on the debris-covered Belvedere Glacier (Anzasca Valley, Italian Alps) with low-cost fixed-wing UAVs and quadcopters. Every year, ground control points and check points were measured with GNSS. Images acquired from UAV were processed with Structure-from-Motion and Multi-View Stereo algorithms to build photogrammetric models, orthophotos and digital surface models, with decimetric accuracy. Annual glacier velocities were derived by combining manually-tracked features on orthophotos with GNSS measurements. Velocities ranging between 17 m y−1 and 22 m y−1 were found in the central part of the glacier, whereas values between 2 m y−1 and 7 m y−1 were found in the accumulation area and at the glacier terminus. Between 2 × 106 m3 and 3.5 × 106 m3 of ice volume were lost every year. A pair of intra-year measurements (October 2017–July 2018) highlighted that winter and spring volume reduction was ∼1/4 of the average annual ice loss. The Belvedere monitoring activity proved that decimetric-accurate glacier models can be derived with low-cost UAVs and photogrammetry, limiting in-situ operations. Moreover, UAVs require minimal data acquisition costs and allow for great surveying flexibility, compared to traditional techniques. Information about annual flow velocities and ice volume variations of the Belvedere Glacier may have great value for further understanding glacier dynamics, compute mass balances, or it might be used as input for glacier flow modelling.
Recentemente, gli Unmanned Aerial Vehicles (UAV) hanno aperto opportunità senza precedenti per il monitoraggio dei ghiacciai alpini, in quanto consentono di ricostruire modelli 3D estesi e ad alta risoluzione. Al fine di valutare le velocità annuali del flusso di ghiaccio e le variazioni di volume, sei misurazioni annuali sono state effettuate tra il 2015 e il 2020 sul ghiacciaio Belvedere coperto di detriti (Valle Anzasca, Alpi italiane) con UAV ad ala fissa e quadricoptero a basso costo. Ogni anno, i punti di controllo a terra e i punti di controllo sono stati misurati con GNSS. Le immagini acquisite dagli UAV sono state elaborate con algoritmi Structure-from-Motion e Multi-View Stereo per costruire modelli fotogrammetrici, ortofoto e modelli digitali di superficie, con precisione decimetrica. Le velocità annuali del ghiacciaio sono state derivate combinando caratteristiche tracciate manualmente sulle ortofoto con misure GNSS. Nella parte centrale del ghiacciaio sono state trovate velocità comprese tra 17 m a-1 e 22 m a-1, mentre valori compresi tra 2 m a-1 e 7 m a-1 sono stati trovati nell'area di accumulo e alla fine del ghiacciaio. Tra 2 × 106 m3 e 3,5 × 106 m3 di volume di ghiaccio sono stati persi ogni anno. Un paio di misurazioni intra-annuali (ottobre 2017-luglio 2018) hanno evidenziato che la riduzione di volume invernale e primaverile era ∼1/4 della perdita media annuale di ghiaccio. L'attività di monitoraggio del Belvedere ha dimostrato che i modelli decimetrici-accurati del ghiacciaio possono essere derivati con UAV a basso costo e fotogrammetria, limitando le operazioni in situ. Inoltre, gli UAV richiedono costi minimi per l'acquisizione dei dati e permettono una grande flessibilità di rilievo, rispetto alle tecniche tradizionali. Le informazioni sulla velocità del flusso annuale e le variazioni di volume del ghiaccio del ghiacciaio Belvedere possono avere un grande valore per comprendere ulteriormente le dinamiche del ghiacciaio, calcolare i bilanci di massa, o potrebbero essere utilizzate come input per la modellazione del flusso del ghiacciaio.
Mid-term monitoring of glacier’s variations with UAVs: The example of the belvedere glacier
Ioli F.;Bianchi A.;Cina A.;De Michele C.;Passoni D.;Pinto L.
2022-01-01
Abstract
Recently, Unmanned Aerial Vehicles (UAV) have opened up unparalleled opportunities for alpine glacier monitoring, as they allow for reconstructing extensive and high-resolution 3D models. In order to evaluate annual ice flow velocities and volume variations, six yearly measurements were carried out between 2015 and 2020 on the debris-covered Belvedere Glacier (Anzasca Valley, Italian Alps) with low-cost fixed-wing UAVs and quadcopters. Every year, ground control points and check points were measured with GNSS. Images acquired from UAV were processed with Structure-from-Motion and Multi-View Stereo algorithms to build photogrammetric models, orthophotos and digital surface models, with decimetric accuracy. Annual glacier velocities were derived by combining manually-tracked features on orthophotos with GNSS measurements. Velocities ranging between 17 m y−1 and 22 m y−1 were found in the central part of the glacier, whereas values between 2 m y−1 and 7 m y−1 were found in the accumulation area and at the glacier terminus. Between 2 × 106 m3 and 3.5 × 106 m3 of ice volume were lost every year. A pair of intra-year measurements (October 2017–July 2018) highlighted that winter and spring volume reduction was ∼1/4 of the average annual ice loss. The Belvedere monitoring activity proved that decimetric-accurate glacier models can be derived with low-cost UAVs and photogrammetry, limiting in-situ operations. Moreover, UAVs require minimal data acquisition costs and allow for great surveying flexibility, compared to traditional techniques. Information about annual flow velocities and ice volume variations of the Belvedere Glacier may have great value for further understanding glacier dynamics, compute mass balances, or it might be used as input for glacier flow modelling.File | Dimensione | Formato | |
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